ARHGEF18 and hereditary optic atrophy: FRMD7 was found in a patient with X-linked congenital nystagmus, as previously reported38; biallelic RTN4IP1 changes were detected in a patient with concomitant RP and optic atrophy, a recently described phenotype39; ARHGEF18 in a patient with autosomal recessive RP40; PRPF6 in a patient with autosomal dominant RP41, and ARSG in a patient with Usher syndrome type 442.